Scan in DATA using a FORM

I urgently need help please. It seems when it comes to scanning in data using a form, it becomes tricky.

I have two input boxes (column 1 & column 2). When one number is scanned (Input Box 1) it must automatically write to the cell A1, TAB to (Input Box 2) it must automatically write to B1, and repeat until done. What I cant figure out, is to make it write automatically to the cell without having to press a button after each scan. Please can someone help me.

Thanks

Tobie